An increasing number of algae blooms may likely account for the increased number of sea lions left stranded, confused, and underfed on California shores this year, scientists say.
A study published Monday in the journal Science found that the algae naturally produces a neurotoxin called domoic acid. The toxin can hurt sea lions' brains, particularly damaging their spatial memory and, in turn, their navigation abilities.
"The behavioral deficits accompanying brain damage with domoic acid are severe, and may negatively impact foraging and navigation in sea lions, driving strandings and mortality," said Emory University cognitive psychologist Peter Cook, who worked on the study while at the University of California-Santa Cruz,
NBC News reported.
"Domoic acid-producing blooms have been in the environment for a very long time, but the current pattern of much larger and more frequent blooms causing more visible damage to marine animals has been going on since the 1980s," he continued.
After performing brain scans on 30 California sea lions, scientists found damage to the hippocampus, the part of the brain that performs spatial functions. In essence, the neurotoxin mimics a chemical that transmits nerve impulses in the brain, causing epilepsy.
From Santa Barbara to Alaska, algae blooms have become more frequent and more intense in recent years, and this year's bloom was the largest on record.
Scientists are now investigating why the blooms have increased, and are looking specifically at ocean pollution from fertilizers, as well as warming ocean temperatures possibly associated with global climate change.
While the overall picture may look grim, the good news is that many sea lions negatively affected by the toxins can oftentimes be rehabilitated, and released back into the wild.
"Hundreds of sea lions end up in stranding facilities each year. A great many of them do die although some can be rehabilitated and survive for some time in the wild," Cook said.
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